Milling tools for shoulder milling, such as shank-end mills, may advantageously be used for machining of shoulders, grooves and edges. For the machining of small details, it is necessary to use a milling tool having a small diameter. For cost-efficiency, it is preferable to use a milling tool which comprises on one hand a tool body, and on the other hand detachable and replaceable milling inserts. However, the milling inserts are subjected to great forces during the milling operation, acting to displace and turn the milling inserts. It is therefore necessary to rigidly fasten the milling inserts in the tool body. This is most often done by providing the milling insert with a centre hole, by means of which a screw or another male fastening member is used to fasten the milling insert in the tool body. There are however disadvantages associated with this fastening method, in particular for milling tools having a small diameter. For example, the small diameter makes it necessary to use small screws, which are generally difficult to handle and which are easy to drop in the process of mounting the milling insert. It may also be difficult to access the hole in the mounting process. Furthermore, the large centre hole weakens the milling insert and makes it less shape stable after pressing and sintering of the insert.
US 2011/0274506 discloses a milling tool and an indexable milling insert for shoulder milling, or for a shank end milling tool, which aim at overcoming the disadvantages of screw mounting. The milling insert is provided with a lock structure including a locking surface arranged on a secondary clearance surface of the milling insert and a coupling structure arranged on an upper side of the milling insert. The milling insert is secured in the tool body by means of the lock structure without the use of any screws or other fastening members. However, mounting of the milling insert is complicated since special tools are required, and the mounted milling insert is not as stable as a screw mounted milling insert.